Many people experience involuntary leg and foot movements, especially during sleep and sometimes during lying down resting while awake. These movements can be tied to sleep disruption that can shorten the duration and reduce the quality of a person's sleep. The characteristics of involuntary leg and foot movements include periodicity (periodic leg movements (PLM)), inter-movement intervals, durations, frequency (at a rate of approximately 5-300/hr), intensity, flexor movement patterns and circadian pattern. They occur when the leg is mostly horizontal with the person either lying down or sitting with legs stretched out. Thus, in addition to detection of movement, detection of horizontal vs. vertical, supine vs. lateral or prone leg position and foot relative to leg positioning are relevant for evaluating these movements. These leg and foot movements can be caused by a number of different factors, either alone or in combination. Such factors include, but are not limited to spinal cord excitability, autonomic arousals, dopaminergic compromise, hypoxic pathway activation, iron deficiency, and genetics, namely a BDBT9 allele.
When these leg and foot movements occur during sleep, they can be clinically significant. They occur with disturbances in sleep even waking up the sufferer. Different patterns of leg and foot movements can indicate different possible disease states such as restless leg syndrome (Willis Ekbom Disease), sleep disordered breathing, iron deficiency, REM behavior disorder, narcolepsy, significant increases in blood pressure, and cardiovascular disease. Leg and foot movements can be an indicator of a worsening condition when present with other serious disorders, such as iron deficiency/anemia, renal disease, and cardiovascular disease.
It would therefore be advantageous to provide an affordable, easily-used device and method for detecting periodic leg movements and allowing accurate measurement of patterns of leg and foot movements in a large number of people in order to quantify whether the patient has a disease state associated with the leg movements.